As a Wi-Fi network continuously gains in popularity, one or even more APs of a wireless network are mostly deployed in a public place, such as an airport, a football field, a shopping mall, or a restaurant. However, in a general technology, a terminal device mostly can access only one AP at a time, and use the AP for data transmission. Therefore, it is difficult for the terminal device to properly utilize network resources. A network signal provided by one AP is unstable. Consequently, data transmission efficiency is easily affected, data transmission between application software and a network is not fluent, and user waiting time is increased.
In one aspect, to maintain data transmission efficiency, a solution currently used for most mobile terminals is to switch a data transmission link to access another AP with a relatively high signal strength. However, if a network is to be switched when data transmission is being performed between a server and an application (APP) of a terminal, a TCP connection established under an original AP needs to be first disconnected, and then a TCP connection under a new AP is established, so that data transmission can be continued. In this case, data needs to be reloaded, which still affects data transmission efficiency and increases user waiting time. Specifically, if the APP is a browser, a web page will be reloaded. If the APP is an online video player such as Youku, data of a previously played video needs to be reloaded and buffered from the beginning. Consequently, data transmission efficiency is still affected, data transmission between application software and a network is still not fluent, and user waiting time is still increased.
In another aspect, a physical network interface card is reused by means of a virtual Wi-Fi technology developed by Microsoft Corporation (Microsoft Corporation), to virtualize one physical network interface card into multiple wireless adapters, so that a terminal can access multiple APs corresponding to multiple wireless networks. However, for virtual connections of multiple wireless local area networks supported by this technology, still only one wireless network can be used within a same time period for data transmission, and this can only implement a direct connection with no need of manual switching or authentication when a data transmission link is switched to another wireless network. In addition, a TCP connection still needs to be re-established during a switching process. Such transmission link switching in essence cannot enable a terminal to properly utilize network resources, data transmission efficiency is still affected, data transmission between application software and a network is still not fluent, and user waiting time is still relatively long.